BIRMINGHAM, Ala. — A 17-year-old girl has been killed in a shooting at dismissal time Wednesday at an Alabama high school and another 17-year-old male student has been injured, authorities said.

Birmingham Interim Police Chief Orlando Wilson said at a news conference that authorities are seeking to determine whether the shooting shortly before 3:30 p.m. Wednesday at Huffman High School was accidental or if a gun since recovered by investigators was intentionally discharged.

School officials said the shooting prompted a brief lockdown at the school in Alabama’s largest city but that students were released and authorities have detetmined that the shooting did not come from “someone from the outside came into the school.” He declined to say who fired the gun or to identify what type of firearm it was.

A police official, Sgt. Bryan Shelton, had told local media earlier that it appeared to be an “accidental shooting.” But Wilson said the circumstances were under investigation and authorities were seeking any witnesses or surveillance video to determine what had happened.

“Right now we have a lot of unanswered questions,” Wilson told reporters. “This should not happen in schools.”

He added, “We are asking questions from the staff, the students, anyone who was in that area.”

The Birmingham City School system said in a statement that the shooting prompted a brief lockdown.

“Two students were involved in a shooting during dismissal,” the school system statement said. “The school was placed on brief lockdown and police were called.” It added that police are investigating the circumstances surrounding the shooting.

Birmingham Mayor Randall Woodfin said the deceased student would have turned 18 in about 30 days and was a senior “who had aspirations and dreams to be a nurse.”

“We are not just talking about some person, talking about losing a part of our future. Our hearts are heavy. I think it’s really important we find a way to mourn with this family,” Woodfin said at the news conference.